Hide and Seek
This reminds me of a funny-only-after-the-event story that happened to someone I know in London. This fellow, with one of those Jewish names that could just as easily be Irish (and there seem to be a lot of those), owns some rental property, and had a tenant who actually was Irish, seemed to be behaving suspiciously, and then suddenly left. So he called the police, who came, searched the flat, found nothing that shouldn't have been there, pronounced it clean, and reassured the landlord that he had nothing to fear, the house wasn't going to blow up one morning. Years passed, and eventually a subsequent tenant pulled up some floorboards, saw explosives hidden under them, and called the police. Who came, saw said explosives, and immediately went to have a serious conversation with the landlord with the Irish-sounding name. Who said "look, I called you years ago when that suss tenant left, and you assured me that there were no bombs hidden in my house!"
I'm not sure what the moral of all this is, except that just because you've already looked somewhere doens't mean that there's nothing still hidden there.